The invention discloses an auxiliary machine for pipe connection in a gas-insulated metal-enclosed transmission line. The auxiliary machine includes a pipe holder, and further includes a support baseand a vertical column mounted on the support base for supporting the pipe holder. The support base is provided with a pushing mechanism for pushing the vertical column. The vertical column is providedwith a lifting mechanism for driving the pipe holder to move up and down, a radial movement mechanism and an axial movement mechanism. The radial movement mechanism and the axial movement mechanism are used for driving the radial movement and the axial movement of the pipe holder respectively. The radial movement mechanism is provided with a rotation mechanism for realizing the rotational motionof the pipe holder. The lifting mechanism, the axial movement mechanism and the radial movement mechanism are all disposed outside the pipe holder. The auxiliary machine can meet the requirement for asmall space between a bellows and a fixing bracket and the requirement for a short distance between adjacent pipes when a multilayer pipeline structure type is used, can realize the all-round adjustment of a pipe unit, and ensures the stability of the pipe unit in an adjustment process.